test: enforce lint style rules (#15085)

.eslintrc.js

lib/config/decrypt.spec.ts

lib/config/index.spec.ts

lib/config/massage.spec.ts

lib/config/migrate-validate.spec.ts

lib/config/migration.spec.ts

lib/config/presets/bitbucket-server/index.spec.ts

lib/config/presets/gitea/index.spec.ts

lib/config/presets/index.spec.ts

lib/config/presets/local/index.spec.ts

lib/config/presets/npm/index.spec.ts

lib/config/presets/util.spec.ts

lib/config/secrets.spec.ts

lib/config/validation.spec.ts

lib/logger/config-serializer.spec.ts

lib/logger/err-serializer.spec.ts

lib/logger/index.spec.ts

lib/logger/pretty-stdout.spec.ts

lib/modules/datasource/aws-machine-image/index.spec.ts

lib/modules/datasource/bitbucket-tags/index.spec.ts